stone mastic ashhalt

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STONE MASTIC ASPHALT

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Stone Mastic Ashhalt

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TMASTIC ASPH

STONE MASTIC ASPHALT

WHAT IS SMAStone mastic asphalt(SMA), also calledstone-matrix asphalt. It is homogeneous mixture of selected well graded aggregate , filler and bitumen in such proportions as to yield a plastic and voidless mass which Act as a very dense impermeable surfacing.It was developed in Germany in the 1960s.

COMPOSITION OF SMACOARSE AGGREGATEFINE AGGREGATEBINDERFILLERFIBRE

PROPERTIES OF COARSE AGGREGATEHardDurableFree from the organic mattrerResistance to strippingWater absorpton should not be greater than 2%

GRADING OF COARSE AGGREGATE Sieve SMA 12.5 mm19.0 mm10012.5 mm90 99 9.5 mm50 85 4.75 mm28 40 2.36 mm16 28 75 m 8 11PROPERTIES OF FINE MATERIALWater absorption of a fine aggregate of any nominal size from any source must not exceed 3.5%. Soundness:- The weighted percent loss from a fine aggregate must not exceed 12% of the test portion.

PROPERTIES OF FILERThe filler shall be limestone powder passing the 0.075 mm sieve .Calcium carbonate content shall not be less than 80% by weight.ADVANTAGE OF SMAResistance to permanent deformation or ruttingGood durability due to high binder contentGood flexibility and resistance to fatigueGood wear resistanceGood surface texture

8DISADVANTAGE OF SMAIncreased cost Increased mixing time and time taken to add extra filler, may result in reduced productivity.Possible delays in opening to trafficInitial skid resistance may be low.

MIX DESIGNHARDNESS NUMBER At the time of manufacturing of 60 to 80 at 25c At the time of laying 10 to 20 at 25cBINDER CONTENT: 14 to 17% by weight of total mix.MIX PROPERTIESDesign Parameter

Design Criteria

Air Voids %

4.0

Voids in Mineral Aggregate, VMA %17 Minimum

Tensile Strength Ratio %

70 Minimum

Draindown %

0.3 Maximum

TENSILE STRENGTH RATIO, TSR

Checks the moisture susceptibility of the asphalt mixture.

whereS1 = average tensile strength of dry subsetS2 = average tensile strength of moisture conditioned subsetTensile Strength Ratio, TSR

DRAINDOWNMass of asphalt mortar that has drained from total asphalt mass

Where:Pi = Initial paper plate mass (grams)Pf = Final paper plate mass (grams)W = Mixture mass (grams)D = % Drain-down